Our body clock

In a previous post we covered breakfast and why skipping it is not conducive to health and fat loss. Today we are going to talk about the rest of the day and in particular, dinner.

As all living beings on this planet, we humans have our own circadian rhythm. Our bodies are attuned to the movement of the planet and, in particular, the change between day and night. Every organ and every cell in our body has its own circadian rhythm. And when night falls things slow down.

Yet, our modern lifestyles are often not very conducive to letting our body follow the rhythm it has been designed to operate at. We prioritise work and getting things done over sitting down to eat at regular times. We often work late, party late and as a consequence eat (and sleep) late.

What happens in our body when we delay eating, especially at dinner?

Here is what the science shows:

➡️ A 20 week study on 420 overweight people trying to lose weight showed that eating lunch after 3pm led to lower weight loss compared to eating lunch at 1pm, irrespective of appetite, age, hormonal status, calorie intake, duration of sleep and macronutrient repartition. "Late Lunchers" were less sensitive to insulin and had lower energy spending and glucose burning at rest.

➡️ A study on 93 overweight women trying to lose weight, all consuming equal amounts of calories, showed that those that ate 50% of their calories at breakfast and 14% at dinner lost 5.1kg more in the 12 week period than those that did the opposite!

➡️ A study where participants were eating 700 kcal at breakfast, 500 kcal at lunch and 200 kcal at dinner has been shown to be more effective for weight loss than doing the opposite - leading to lower blood sugar, lower insulin and lower insulin resistance.

➡️ Students who ate > 50% of their calories 8 hrs before what is known as Dim Light Melatonin Onset (DLMO), (i.e the time our body starts making melatonin in response to the light changing) were significantly leaner than those that consumed the same calories approximately 4hr before. Eating in the 2hr window before bedtime multiplied 5x the risk of becoming obese.

➡️ A 2020 study on 16 normal weight people showed that postprandial thermogenesis was 2.5x higher after breakfast than after dinner. In plain English, we burn more calories after eating the same food in the morning compared to in the evening.

Why is all this happening?

It largely comes down to insulin. Or rather how sensitive we are to it. Turns out we are more sensitive to insulin in the first half of the day. It is easier for the glucose from the starches or sugars we eat to enter our cells with the help of insulin and become energy when we eat them in the morning rather than in the evening. Our metabolism slows down in the evening too.

That makes sense. In the evening, as night falls, we tend to move less, we are supposed to go to bed. We do not need to be energy burning machines at that time of day. Our pancreas kind of wants to take it slow then and is not very happy dishing out bucketloads of insulin in response to pizza night. Our body wants to start the rest and repair process, not keep working on digestion.

What if we don't listen to that and have that late night curry?

Well, our stomach will empty at a slower rate than normal, 

Our blood sugar will stay higher for longer.

We won't use that energy for movement and we will put it into storage … as fat.

Our pancreas will not be pleased. It prefers to work more in the morning.

Neither will our liver - it does not like seeing all that insulin at that time of night, so it will start becoming more resistant to it. 

Neither will our gut bugs (the microbiome) and that will have a negative effect on our metabolism and the absorption of carbs and fats.

Our sleep will be disturbed - which in itself is not great for fat loss or insulin sensitivity (my continuous glucose monitor screams that in my face every time I have a crappy night of sleep!)

And, surprise surprise, we wake up the next morning after that late dinner and we are really not hungry for breakfast.

And so it goes. No (or insignificant breakfast), quick lunch at the desk or on the go, biscuit in the afternoon, eat All The Things for dinner and repeat. How many of us have been there?  

Ok, that's enough of the biochemistry.

Now what do we do about it?

Life is going to happen. That's ok, perfection is never the goal and there is no need to stress about it.

However, as I've suggested doing with breakfast, try to establish your baseline and return to it as often as you can, making the late dinner the exception rather than the rule.

And by late I mean after 8pm.

What if you have a habit of eating late because that's what you have always done or because your working hours are such that you get home late?

In that case, I would suggest aiming to have a bigger healthy snack in the afternoon, around 4-5pm. Go for nuts, fruit, diary, a piece of dark chocolate, if you like it. Make it as much of a little meal as you can. Pack some leftovers with you from the day before, a piece of chicken, some easy veg (like carrots, baby tomatoes) with a small piece of bread. Be creative.

You will see then that you will not be as hungry for dinner and you will eat  a lot less later.

Start like that and try to find ways of gradually increasing the size of your afternoon snack and decreasing dinner as much as possible.

The goal is to stop eating at least 2 hrs before going to bed, if possible more. Aim for at least 12 hrs between dinner and breakfast. 

With this system, your body will do its clean up and repair operation undisturbed and you will wake up bright eyed and bushy tailed and ready for a nice protein rich breakfast. You will have reversed the trend and set yourself up for less cravings and more energy and mental clarity during your day. 

Try it. I am very confident that your body will thank you for it 😉